When doing a pattern I find it bennefitting to start with rows with an uneven number of groups in it, since the middle one of these will often be placed centered in the pattern. But you still have to do a bit of guessing with this one.
I couldnt of done this without Ekkonic's comment thanks :) And for anyone else who needs help the top row/bottom rows are placed at 5,13,21. The end picture is of 3 squares (all on an edge - a diamond shape i think) which have lines through them to make 4 "diamond shapes" inside each bigger one.
Use symmetry to place the middle three columns. Use C12 and C14 as examples for where to place all the columns of 4 points. R4 and R6 are matching, so the rest of their dots need to go in columns with two pixels. R3 and R7 are also matched.
And for anyone else who needs help the top row/bottom rows are placed at 5,13,21. The end picture is of 3 squares (all on an edge - a diamond shape i think) which have lines through them to make 4 "diamond shapes" inside each bigger one.